DE102019203667A1 - CARRIER FOR ELECTRICALLY HEATED CATALYST AND EXHAUST GAS CLEANING DEVICE - Google Patents

Abstract

A support for an electrically heated catalyst includes: a honeycomb structure; and a pair of metal electrode parts. A metal electrode part of the pair of metal electrode parts is disposed on a side opposite to the other metal electrode part via a center of the honeycomb structure. A part or both parts of the pair of metal electrode parts include: a plate-shaped main part; and a plurality of tongue pieces protruding from the main body, respectively. A part of each tongue piece is in contact with the honeycomb structure.

Description

TECHNICAL AREA

The present invention relates to a support for an electrically heated catalyst. More particularly, the present invention relates to a support for an electrically heated catalyst comprising a honeycomb structure and a pair of metal electrode parts arranged to oppose each other across a center of the honeycomb structure in which breakage of the honeycomb structure occurs due to a difference in thermal expansion coefficient the honeycomb structure and the metal electrode parts can be effectively prevented. The present invention also relates to an exhaust gas purification device using a support for an electrically heated catalyst.

Conventionally, an element in which a catalyst is applied to a honeycomb structure of cordierite or silicon carbide is used to treat harmful substances in exhaust gases discharged from automobile engines (see Patent Document 1). Such a honeycomb structure usually has a columnar honeycomb structure which includes partitions defining a plurality of cells extending from one end face to the other end face to form flow paths for an exhaust gas.

For the treatment of the exhaust gas with the catalyst applied to the honeycomb structure, a temperature of the catalyst must be raised to a predetermined temperature. However, when starting the engine, the catalyst temperature is lower, which conventionally causes a problem that the exhaust gas is not sufficiently cleaned. Therefore, a system called electrically heated catalyst (EHC) was developed. In the system, electrodes are disposed on a conductive ceramic honeycomb structure, and the honeycomb structure itself generates heat by electric conduction, whereby the temperature of the catalyst applied to the honeycomb structure is increased to an activation temperature before starting or starting the engine.

Electrical connection to external wiring is required for current to flow through the EHC. However, due to a difference in coefficient of linear expansion between a surface electrode and wiring forming metal material and a ceramic material forming a support, thermal stress is generated during electrical heating. Therefore, there is a need for an element that also performs a voltage buffering function so that the thermal stress due to the difference in coefficient of linear expansion does not affect the carrier for the EHC.

As one of several approaches, Patent Document 1 discloses that a wiring for supplying a pair of surface electrodes each extending in an axial direction of a support surface is formed with electric current from the outside to a comb-tooth shape and also by thermal spraying at a plurality of positions the same comb tooth is attached to provide a bent portion between the positions, whereby a thermal stress (thermal stress) due to a difference in the coefficient of linear expansion between the metal wiring and a ceramic carrier is reduced.

PUBLICATION LIST

patent literature

Patent Document 1: Japanese Patent No. 5761161 B

BRIEF DESCRIPTION OF THE INVENTION

However, when the plurality of dots are fixed at a plurality of positions on the same comb teeth, the expansion differs depending on the point due to a distribution of heat generation or the like, and the load is applied to the fixed points (contact points) so that the contact points can break. Further, although it is assumed that bent parts are provided to release the stress, the bent parts can not break a torsional stress, so that the contact points may break.

Further, the above document also mentions a method of attaching the same electrode at one point only. However, it is believed that as the method reduces the number of contact points, the corresponding current width becomes narrower.

The present invention has been made in view of the above problems. An object of the present invention is to provide a support for an electrically heated catalyst comprising a honeycomb structure and a pair of metal electrode parts arranged to face each other across a center of the honeycomb structure capable of causing breakage of the honeycomb structure due to a honeycomb structure To effectively prevent differences in thermal expansion coefficient between the honeycomb structure and the metal electrode parts. Further, an object of the present invention is to provide an exhaust gas purification device using the carrier for the electrically heated catalyst.

1. (1) Ein Träger für einen elektrisch beheizten Katalysator, enthaltend:
   • eine Wabenstruktur; und
   • ein Paar von Metallelektrodenteilen, wobei ein Metallelektrodenteil des Paars von Metallelektrodenteilen auf einer dem anderen Metallelektrodenteil über einen Mittelpunkt der Wabenstruktur hinweg entgegengesetzten Seite angeordnet ist;
   • wobei einer oder beide des Paars von Metallelektrodenteilen enthält beziehungsweise enthalten:
     • einen plattenförmigen Hauptteil; und
     • eine Vielzahl von jeweils aus dem Hauptteil vorstehenden Zungenstücken, und
     • wobei ein Teil jedes Zungenstücks mit der Wabenstruktur in Kontakt steht.
2. (2) Eine Abgasreinigungsvorrichtung, enthaltend:
   • den Träger für den elektrisch beheizten Katalysator gemäß Punkt (1), wobei der Träger in einem Abgasströmungsweg zum Strömenlassen eines Abgases aus einem Motor angeordnet ist; und
   • ein zylindrisches Metallelement zur Aufnahme des Trägers für den elektrisch beheizten Katalysator.

Through in-depth research, the inventors of the present invention have found that the above problems can be solved by providing a plurality of tongue pieces projecting from a main part of each of metal electrode parts and contacting the tongue pieces with a honeycomb body, thus being prevented For example, the honeycomb structure may be subjected to excessive stress by thermal stress due to a difference in linear expansion coefficient between the metal electrode parts and the honeycomb structure. Thus, the present invention will be described as follows:

1. (1) A carrier for an electrically heated catalyst containing:
   • a honeycomb structure; and
   • a pair of metal electrode parts, wherein a metal electrode part of the pair of metal electrode parts is disposed on a side opposite to the other metal electrode part across a center of the honeycomb structure;
   • wherein one or both of the pair of metal electrode parts contains or contains:
     • a plate-shaped body; and
     • a plurality of tongue pieces respectively protruding from the main body, and
     • wherein a part of each tongue piece is in contact with the honeycomb structure.
2. (2) An exhaust gas purification device containing:
   • the support for the electrically heated catalyst as described in (point 1 ), wherein the carrier is arranged in an exhaust gas flow path for flowing an exhaust gas from a motor; and
   • a cylindrical metal member for receiving the support for the electrically heated catalyst.

According to the present invention, the support for the electrically heated catalyst including the honeycomb structure and the pair of metal electrode parts, wherein one metal electrode part of the pair of metal electrode parts is disposed on a side opposite to the other metal electrode part via the center of the honeycomb structure, may break the honeycomb structure the difference in the thermal expansion coefficient between the honeycomb structure and the metal electrode parts effectively.

list of figures

• 1 Fig. 10 is a view showing an example of a honeycomb structure of the present invention.
• 2 is a sectional view of a honeycomb structure according to an embodiment of the present invention.
• 3 FIG. 12 is a view showing a center angle of each electrode layer in an embodiment of the present invention. FIG.
• 4 Fig. 12 is a view showing an arrangement of metal electrode parts in an embodiment of the present invention.
• 5 FIG. 15 is a perspective view showing a metal electrode part. FIG 1 according to an embodiment of the present invention.
• 6 FIG. 15 is a perspective view showing a metal electrode part. FIG 1A according to another embodiment of the present invention.
• 7 FIG. 15 is a perspective view showing a metal electrode part. FIG 1B according to yet another embodiment of the present invention.
• 8th FIG. 15 is a perspective view showing a metal electrode part. FIG 1C according to yet another embodiment of the present invention.
• The 9 (a), (b), (c) and 9 (d) are views illustrating planar shapes of tongue pieces 7A . 7B . 7C respectively 7D ,
• The 10 (a), (b) and 10 (c) are views illustrating planar shapes of tongue pieces 7E . 7F respectively 7G ,
• 11 is a view showing a shape of a tongue piece.
• 12 is a view showing a bent portion of a tongue piece.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, embodiments of a support for an electrically heated catalyst according to the present invention will be described with reference to the drawings. However, the present invention is not limited to the embodiments, and various changes, modifications, and improvements can be made with the same skill without departing from the scope of the present invention.

honeycomb structure

1 Fig. 10 is a view showing an example of a honeycomb structure of the present invention. For example, contains the honeycomb structure 10 : porous partitions 11 containing a variety of cells 12 define the cells 12 Forming flow paths for a fluid, wherein the cells extend from an inflow end face, which is an end face on a fluid inflow side, to an outflow end face, which is an end face on a Fluidausströmseite; and an outer peripheral wall disposed at the outermost edge. The number, arrangement, shape and the like of the cells 12 as well as the thickness of each partition 11 and the like are not limited and may be made as desired as desired.

A material of the honeycomb structure 10 is not particularly limited as long as it is conductive, and metals, ceramics and the like can be used. Particularly, from the viewpoint of compatibility of heat resistance and conductivity, the material is the honeycomb structure 10 preferably, especially, a silicon-silicon carbide composite or silicon carbide, and is more preferably a silicon-silicon carbide composite or silicon carbide. Also, tantalum silicide (TaSi ₂ ) and chromium silicide (CrSi ₂ ) may be added to lower the specific electrical resistance of the honeycomb structure. The sentence "The honeycomb structure 10 mainly consists of a silicon-silicon carbide composite "means that the honeycomb structure 10 90 or more mass% of silicon-silicon carbide composite (total mass), based on the entire honeycomb structure. Here, as for the silicon-silicon carbide composite, it contains silicon carbide particles as an aggregate and silicon as a bonding material for bonding the silicon carbide particles, and a plurality of silicon carbide particles is bonded by silicon to pores between the silicon carbide particles to build. The sentence "The honeycomb structure 10 consists mainly of silicon carbide "means that the honeycomb structure 10 90 or more mass% of silicon carbide (total mass), based on the entire honeycomb structure.

The specific electrical resistance of the honeycomb structure 10 may be adjusted as needed, depending on the voltage to be applied, including but not limited to, for example, from 0.001 to 200 Ωcm. For a higher voltage greater than or equal to 64 V, it may be 2 to 200 Ωcm and typically 5 to 100 Ωcm. Further, it may be 0.001 to 2 Ωcm and more typically 0.001 to 1 Ωcm and more typically 0.01 to 1 Ωcm for a lower voltage of less than 64V.

Every partition 11 the honeycomb structure 10 preferably has a porosity of 35 to 60% and more preferably 35 to 45%. A porosity smaller than 35% may result in more deformation during firing. A porosity greater than 60% may result in decreased strength of the honeycomb structure. Porosity is a value measured with a mercury porosimeter.

Every partition 11 the honeycomb structure 10 preferably has an average pore size of 2 to 15 μm, and more preferably 4 to 8 μm. An average pore diameter of less than 2 microns may result in excessively high resistivity. An average pore diameter of over 15 μm may result in excessively low resistivity. The average pore size is a value measured with a mercury porosimeter.

The shape of each cell 12 in a cross-section orthogonal to a flow path direction of each cell is not limited, but it may preferably be a square, a hexagon, an octagon, or a combination thereof. Of these, the square and hexagonal shapes are preferable. Such a honeycomb form has a lower pressure loss when an exhaust gas passes through the honeycomb structure 10 flows, and an improved cleaning performance of the catalyst result.

The outer shape of the honeycomb structure 10 is not particularly limited as long as it is a columnar shape, and may be, for example, a shape such as a columnar shape (cylindrical shape), a columnar shape having oval bases, and a columnar shape having polygonal (square, pentagonal, hexagonal, pentagonal, octagonal, and like) bases and the like. Furthermore, what the size of the honeycomb structure 10 as a matter of interest, in order to increase the heat resistance, the base areas of the honeycomb structure preferably have an area of 2,000 to 20,000 mm ^2, and more preferably 4,000 to 10,000 mm ² (thereby preventing cracks generated in a circumferential direction of the outer peripheral side wall). Further, an axial length of the honeycomb structure 10 for the purpose of enhancing the heat resistance, preferably 50 to 200 mm, and more preferably 75 to 150 mm (whereby cracks generated in a direction parallel to a central axis direction in the outer peripheral side wall are prevented).

Furthermore, the honeycomb structure 10 by applying a catalyst to the honeycomb structure 10 be used as a catalyst support.

The production of the honeycomb structure may be performed according to a method of manufacturing a honeycomb structure in a known method for producing a honeycomb structure. For example, a molding material is first prepared by adding silicon carbide powder (silicon carbide), metallic silicon powder (metallic silicon), a binder, one or more wetting agents, a pore former, water, and the like. Preferably, a mass of metallic silicon, based on the sum of the mass of silicon carbide powder and the mass of metallic silicon, should be 10 to 40 mass%. The average particle diameter of the silicon carbide particles in the silicon carbide powder is preferably from 3 to 50 μm, and more preferably from 3 to 40 μm. The average particle diameter of the metallic silicon particles in the metallic silicon powder is preferably 2 to 35 μm. The average particle diameter of both the silicon carbide particles and the metallic silicon particles when measuring the frequency distribution of the particle size by the laser diffraction method corresponds to a volume average diameter arithmetic mean. The silicon carbide particles are fine particles of silicon carbide which constitute the silicon carbide powder, and the metallic silicon particles are fine particles of metallic silicon which form the metallic silicon powder. It should be noted that this is the formulation for molding raw materials in the case where the material of the honeycomb structure is the silicon-silicon carbide composite material. In the case where silicon carbide is the material of the honeycomb structure, no metallic silicon is added.

Examples of the binder include methylcellulose, hydroxypropylmethylcellulose, hydroxypropoxylcellulose, hydroxyethylcellulose, carboxymethylcellulose, polyvinyl alcohol, and the like. Of these, methyl cellulose is preferably used in combination with hydroxypropoxyl cellulose. The binder content is preferably 2.0 to 10.0 parts by mass, when the total mass of the silicon carbide powder and the metallic silicon powder 100 Mass parts is.

The water content is preferably 20 to 60 parts by mass, when the total mass of the silicon carbide powder and the metallic silicon powder 100 Mass parts is.

Wetting agents which can be used include ethylene glycol, dextrin, fatty acid soaps, polyalcohol and the like. These may be used alone or in combinations of two or more agents. The wetting agent content is preferably 0.1 to 2.0 parts by mass, when the total mass of the silicon carbide powder and the metallic silicon powder 100 Mass parts is.

The pore-forming agent is not particularly limited as long as the pore-forming agent pores even after firing, and contains, for example, graphite, starch, foamable resins, water-absorbent Resins, silica gel and the like. The pore former content is preferably 0.5 to 10.0 parts by mass, when the total mass of the silicon carbide powder and the metallic silicon powder 100 Mass parts is. An average particle diameter of the pore-forming agent is preferably 10 to 30 μm. If it is smaller than 10 μm, insufficient pores may not be formed. If it is larger than 30 μm, a template may be clogged by the pore former during molding. When measuring the frequency distribution of the particle size by means of the laser diffraction method, the average particle size of the pore-forming agent corresponds to a volume-related arithmetic mean diameter. When the pore-forming agent is the water-absorbent resin, the average particle diameter of the pore-forming agent is an average particle diameter after water absorption.

Then, the resulting molding raw materials are kneaded to form a green body, and then the green body is extruded to produce a honeycomb structure. In extrusion molding, a die having a desired overall shape, honeycomb shape, bulkhead thickness, honeycomb density and the like can be used. Preferably, the resulting honeycomb structure is dried. If the length in the central axis direction of the honeycomb structure is not the desired length, the two end faces of the honeycomb structure can be cut to the desired length.

The dried honeycomb body is then fired to produce a honeycomb structure. Prior to firing, calcination may preferably be performed to remove the binder and the like. The calcination is preferably carried out in an air atmosphere for 0.5 to 20 hours at a temperature of 400 to 500 ° C. The calcining and firing methods are not limited, and they may be carried out using an electric furnace, a gas furnace or the like. The firing may preferably be carried out in an inert atmosphere such as nitrogen and argon for 1 to 20 hours at a temperature of 1400 to 1500 ° C. After firing, oxygenating treatment is preferably carried out at a temperature of 1200 to 1350 ° C for 1 to 10 hours to improve durability.

electrode layer

As in the 1 and 2 shown has the outer peripheral wall of the honeycomb structure 10 According to this embodiment, a pair of electrode layers 101 . 101b on. Each of the electrode layers 101 . 101b is formed into a stripe shape which extends in the direction of expansion of the cell 12 the honeycomb structure 10 extends. In one to the expansion direction of the cell 12 orthogonal cross-section of the honeycomb structure 10 is an electrode layer of the pair of electrode layers 101 . 101b on one of the other electrode layers over a center of the honeycomb structure 10 arranged on opposite side. The pair of electrode layers 101 . 101 b is not essential to the present invention. However, such a configuration enables the suppression of any distortion of one in the honeycomb structure 10 flowing current and the suppression of any distortion of a temperature distribution in the honeycomb structure 10 upon application of an electrical voltage, which is desirable.

The electrode layers 101 . 101b are formed of a conductive material. Preferably, each of the electrode layers should 101 . 101b mainly of silicon carbide particles and silicon, and more preferably each of the electrode layers 101 . 101b except for impurities which are usually contained, formed by using silicon carbide particles and silicon as raw materials. As used herein, the phrase "consisting primarily of silicon carbide particles and silicon" means that the total mass of silicon carbide particles and silicon 90 or more mass% corresponds to the mass of the entire electrode layer. Thus, each of the electrode layers exists 101 . 101b mainly of silicon carbide particles and silicon, whereby constituents of each of the electrode layers 101 . 101b and components of the honeycomb structure 10 are similar or similar (which is a case in which the material of the honeycomb structure is silicon carbide). Therefore, the electrode layers have 101 . 101b and the honeycomb structure same or close to each other thermal expansion coefficient values. Further, since the materials are similar or similar to each other, adhesion between the electrode layers also increases 101 . 101b and the honeycomb structure 10 to. Therefore, even if thermal stress is applied to the honeycomb structure, it is possible to prevent the electrode layers from being damaged 101 . 101b away from the honeycomb structure 10 Peel off or connecting parts between the electrode layers 101 . 101b and the honeycomb structure 10 break.

Further, in the direction of expansion of the cell 12 orthogonal cross section, a center angle α of each of the electrode layers 101 . 101b preferably 60 to 120 °. Further, the center angle α is one of the electrode layers 101 . 101b preferably equal to 0.8 to 1.2 times the center angle α of the other of the electrode layers 101 . 101b and more preferably 1.0 times (ie same size). This can enable the suppression of any distortion of the current flowing through the outer periphery and through the central portion of the honeycomb structure when an electric voltage is applied between the pair of electrode layers 101 . 101b is created. In the outer periphery as well as in the central portion of the honeycomb structure, any distortion of heat generation can be suppressed.

As used herein, the midpoint angle α denotes one through the two end portions of the electrode layers 101 . 101b and a center of the honeycomb connecting straight lines formed angle in the direction of extension of the cell 12 orthogonal section (see 3 ). In 3 are the midpoint angles α of the pair of electrode layers 101 . 101b equal.

In the honeycomb structure 10 According to the present embodiment, the specific electric resistance of the electrode layers 101 . 101b preferably lower than the electrical resistivity of the outer peripheral wall of the honeycomb structure 10 , Furthermore, the specific electrical resistance of the electrode layers is 101 . 101b more preferably between 0.1 and 10% and more preferably between 0.5 and 5% of the electrical resistivity of the outer peripheral wall of the honeycomb structure 10 , If it is lower than 0.1%, a thickness of one increases to the "end parts of the electrode part" within the electrode layer 101 . 101b flowing current when an electrical voltage to the electrode layers 101 . 101b is applied, so that by the honeycomb structure 10 flowing electricity can be easily distorted. In addition, it may be for the honeycomb structure 10 difficult to generate heat evenly. If it is higher than 10%, a strength of one takes in the electrode layers 101 . 101b spreading current when an electrical voltage to the electrode layers 101 . 101b is created, and can by the honeycomb structure 10 flowing electricity can be easily distorted. In addition, it may be for the honeycomb structure 10 difficult to generate heat evenly.

Each of the electrode layers 101 . 101b preferably has a thickness of 0.01 to 5 mm, and more preferably 0.01 to 3 mm. Such values of thickness can contribute to uniform heat generation of the honeycomb structure. When the thickness of each of the electrode layers 101 . 101b is less than 0.01 mm, the specific electrical resistance increases and even heat generation may not be possible. When the thickness of each of the electrode layers 101 . 101b is greater than 5 mm, it can lead to a break when canning.

As in 1 shown extends in the honeycomb structure 10 According to the present embodiment, each of the electrode layers 101 . 101b in the direction of expansion of the cell 12 the honeycomb structure 10 and is each of the electrode layers 101 . 101b formed in a "strip form extending between both end parts (two end faces). Thus, in the honeycomb structure 10 According to the present embodiment, the pair of electrode layers 101 . 101b arranged so that it is between the two end parts of the honeycomb structure 10 extends. This can more effectively suppress the distortion of the current in the axial direction of the honeycomb structure (that is, the expansion direction of the cell 12 ) when an electrical voltage between the pair of electrode layers 101 . 101b is created. As used herein, the phrase "the electrode layer 101 . 101b is between the two end parts of the honeycomb structure 10 formed (arranged) "the following meaning: an end part of each of the electrode layers 101 . 101b stands with an end part (a front side) of the honeycomb structure 10 in contact, and the other end part of each of the electrode layers 101 . 101b stands with the other end part (the other end face) of the honeycomb structure 10 in contact.

On the other hand, a preferred embodiment is also a state in which at least one end portion of each of the electrode layers 101 . 101b in the "expansion direction of the cell 12 the honeycomb structure 10 "not with the end part (the front side) of the honeycomb structure 10 is in contact (not up to him (her) is enough). This can improve the thermal shock resistance of the honeycomb structure.

In the honeycomb structure 10 In the present embodiment, each of the electrode layers is 101 . 101b is formed in such a shape that a flat rectangular member is bent along an outer circumference of a columnar shape such as in Figs 1 and 2 shown. Here is a shape when the curved electrode layer 101 . 101b is deformed into a non-bent, planar element, as a "planar shape" of the electrode layer 101 . 101b designated. The "flat form" of the 1 to 3 shown electrode layer 101 . 101b is a rectangle. By an "outer edge shape of the electrode layer" as used herein is meant an "outer edge shape of the planar shape of the electrode layer".

In the honeycomb structure 10 According to the present embodiment, the outer edge shape of the stripe-shaped electrode layer may be a shape in which each of the rectangular corner parts in one curved shape is formed. Such a shape makes it possible to improve the thermal shock resistance of the honeycomb structure. A preferred embodiment is that the outer edge of the strip-shaped electrode layer has a shape in which the rectangular corner parts are chamfered straight. Such a shape may allow an improvement in the thermal shock resistance of the honeycomb structure.

In the honeycomb structure 10 According to the present embodiment, the length of the current path in the cross section orthogonal to the extension direction of the cell is preferably less than or equal to 1.6 times the diameter of the honeycomb structure. If it is larger than 1.6 times, it may consume unnecessary energy. As used herein, the "current path" refers to a path through which a current flows. The "length of the current path" denotes a length in the "orthogonal to the extension direction of the cell cross-section" of the honeycomb structure, which corresponds to 0.5 times the length of the "outer periphery" through which current flows. Thus, the maximum length of the "current paths through which current flows" in the "orthogonal to the extension direction of the cell cross-section" of the honeycomb structure is meant. The "length of the current path" is when the irregularities are formed on the outer periphery or the slit opening is formed to the outer periphery in the honeycomb structure, a value measured along surfaces within irregularities or a slit. Therefore, for example, when the slit opening is formed to the outer periphery in the honeycomb structure, the "length of the current path" is longer by a length which is approximately twice the depth of the slit.

The specific electrical resistance of the electrode layers 101 . 101b is preferably 0.1 to 1.0 Ωcm, and more preferably 0.1 to 50 Ωcm. At such values of the resistivity of the electrode layers 101 . 101b The pair of electrode layers function 101 . 101b effective as electrodes in a pipe through which a high-temperature exhaust gas flows. When the specific electrical resistance of the electrode layers 101 . 101b is less than 0.1 Ωcm, the temperature of the honeycomb portion near both ends of each of the electrode layers tends 101 . 101b in the cross section orthogonal to the extension direction of the cell, to rise. When the specific electrical resistance of the electrode layers 101 . 101b is larger than 100 Ωcm, hardly any current flows, so that it may be difficult to play a role as an electrode. The electrical resistivity of each of the electrode layers 101 . 101b is a value at a temperature of 400 ° C.

Each of the electrode layers 101 . 101b preferably has a porosity of 30 to 60% and more preferably 30 to 55%. Such values of the porosity of each of the electrode layers 101 . 101b can provide a suitable electrical resistivity. When the porosity of each of the electrode layers 101 . 101b less than 30%, deformation occurs during production. When the porosity of each of the electrode layers 101 . 101b is greater than 60%, the specific electrical resistance may increase excessively. Porosity is a value measured with a mercury porosimeter.

Each of the electrode layers 101 . 101b preferably has an average pore diameter of 5 to 45 μm, and more preferably 7 to 40 μm. Such values of the average pore diameter of each of the electrode layers 101 . 101b can provide a suitable electrical resistivity. When the average pore diameter of each of the electrode layers 101 . 101b is smaller than 5 μm, the specific electrical resistance may become too high. When the average pore diameter of each of the electrode layers 101 . 101b greater than 45 μm, the strength of each of the electrode layers can be 101 . 101b they can be weakened and break them sooner. The average pore diameter is a value measured with a mercury porosimeter.

When each of the electrode layers 101 . 101b mainly composed of the "silicon-silicon carbide composite" have in each of the electrode layers 101 . 101b contained silicon carbide particles preferably has an average particle diameter of 10 to 60 microns and more preferably from 20 to 60 microns. Such values of the average particle diameter of the electrode layers 101 . 101b contained silicon carbide particles can allow the specific electrical resistance of the electrode layers 101 . 101b within a range of 0.1 to 100 Ωcm. When the average particle diameter of the in the electrode layers 101 . 101b contained silicon carbide particles is smaller than 10 microns, the specific electrical resistance of the electrode layers 101 . 101b get too high. When the average particle diameter of the in the electrode layers 101 . 101b The silicon carbide particles contained larger than 60 microns, the strength of each of the electrode layers 101 . 101b they can be weakened and break them sooner. The average particle diameter in the electrode layers 101 . 101b contained silicon carbide particles is a measured by a laser diffraction method value.

When each of the electrode layers 101 . 101b consists mainly of the "silicon-silicon carbide composite", there is a ratio of one in the electrode layers 101 . 101b contained silicon mass to that in the electrode layers 101 . 101b Preferably, the "sum of the respective masses of silicon carbide particles and silicon" contained in a range of 20 to 40 mass%. More preferably, the ratio of the silicon mass to that in the electrode layers 101 . 101b contained "sum of the respective masses of silicon carbide particles and silicon" 25 to 35 mass%. At such values of the ratio of the silicon mass to that in the electrode layers 101 . 101b contained "sum of the respective masses of silicon carbide particles and silicon", the specific electrical resistance of the electrode layers 101 . 101b in a range of 0.1 to 100 Ωcm. When the ratio of the silicon mass to that in the electrode layers 101 . 101b If the sum of the respective masses of silicon carbide particles and silicon is less than 20 mass%, the specific electrical resistance may become too high, and if it is larger than 40 mass%, it may rather be deformed during production come.

Metal electrode part

As in 4 shown is the honeycomb structure 10 over the electrode layers 101 . 101b with a pair of metal electrode parts 1 . 1 in contact. Here, each of the metal electrode parts points 1 . 1 a plate-shaped body 2 and a plurality of tongue pieces protruding from the main body 3 (two in the figure). A part of every tongue piece 3 stands with the honeycomb structure 10 in contact (in the figure it stands over one of the electrode layers 101 . 101b with the honeycomb structure 10 in contact). According to the arrangement, the metal electrode parts 1 . 1 when over the electrode layers 101 . 101b An electrical voltage is applied to be energized to the honeycomb structure 10 To generate heat as joule heat. Therefore, the honeycomb structure 10 suitable to be used as heating. The applied voltage is preferably 12 to 900 V, and more preferably 64 to 600 V. However, the applied voltage may be changed as needed.

5 FIG. 15 is a perspective view showing a metal electrode part. FIG 1 according to an embodiment of the present invention. The metal electrode part 1 has a main part 2 with the shape of a flat plate. A variety of tongue pieces 3 is in the figure above the main part 2 arranged regularly. Every tongue piece 3 contains one of the main part 2 rising part 3a and one laterally from the rising part 3a protruding flat part 3b , Every tongue piece 3 is about a piece 20 at the foot of the tongue piece with the main part 2 connected.

In this embodiment, each tongue piece 3 by cutting out the main body 2 formed, leaving a through hole 4 having substantially the same shape and size as those of the tongue piece 3 is formed. A flat part 3b is in contact with an upper electrochemical cell.

6 FIG. 15 is a perspective view showing a metal electrode part. FIG 1A according to another embodiment of the present invention. The metal electrode part 1A contains a major part 2 with the shape of a flat plate. A variety of tongue pieces 13 is in the figure above the main part 2 arranged regularly. Every tongue piece 13 contains one of the main part 2 rising part 13a , one laterally from the rising part 13a protruding flat part 13b and a sloping part 13c which is from the flat part 13b to one side of the through-hole 4 extends. The flat part 13b is in contact with the upper electrochemical cell. Every tongue piece 13 is about a piece 20 at the foot of the tongue piece with the main part 2 connected.

7 FIG. 15 is a perspective view showing a metal electrode part. FIG 1B according to yet another embodiment of the present invention. The metal electrode part 1B has a main part 2 with the shape of a flat plate. A variety of tongue pieces 23 is in the figure above the main part 2 arranged regularly. Every tongue piece 23 contains one of the main part 2 rising part 23a , a variety of bent parts 23b . 23c . 23d . 23e , which with the rising part 23a connected, and a flat part 23f , The flat part 23f is in contact with the upper electrochemical cell. Every tongue piece 23 is about a piece 20 at the foot of the tongue piece with the main part 2 connected.

8th FIG. 15 is a perspective view showing a metal electrode part. FIG 1C according to yet another embodiment of the present invention. The metal electrode part 1C contains a major part 2 with the shape of a flat plate. A variety of tongue pieces 33 is in the figure above the main part 2 arranged regularly. Each of the tongue pieces 33 contains one of the main part 2 rising part 33a , a bent part 33b , which is related to this, and a flat part 33c , which with the bent part 33b related. The flat part 33c stands with the upper electrochemical cell in contact. Every tongue piece 33 is about a piece 20 at the foot of the tongue piece with the main part 2 connected.

Further, the shape of the main part 2 is not particularly limited as long as it is a plate shape and may be a flat plate shape or a curved plate shape (see 4 (b) ). If the main part 2 has the shape of a bent plate, the curved shape is preferably in the shape of the side surface of the honeycomb structure 10 match. That is, a distance between the main body 2 and the honeycomb structure 10 is preferably constant.

The flat shape of each tongue piece is not particularly limited. For example, tongue pieces 7A , 7B, as in the 9 (a) and 9 (b) shown to be rectangular. Furthermore, a tongue piece 7C , as in 9 (c) shown to have an arched shape. As in 9 (d) shown, can be a tongue piece 7D have an oval shape.

Furthermore, a tongue piece 7E , as in 10 (a) shown to have a polygonal shape. Furthermore, a tongue piece 7F , as in 10 (b) shown to have a trapezoidal shape. Furthermore, a tongue piece 7G , as in 10 (c) shown to have a star shape. The tongue pieces may also have other various irregular shapes.

The size of each tongue piece is not particularly limited. In order to increase the space for air permeability and deformation, each tongue piece preferably has a height greater than or equal to 0.3 mm, and more preferably greater than or equal to 1.0 mm. On the other hand, when each tongue piece is too high, a degree of utilization of a gas recedes, so that the height of the tongue piece is preferably less than or equal to 5.0 mm. The height of the tongue piece corresponds to the longest distance of vertical distances of each part of the tongue pieces to the main part.

A part of every tongue piece 3 stands with the honeycomb structure 10 in contact (see 4 ). When the electrode layer is mounted on the surface of the honeycomb structure, a part of the tongue piece stands 3 over the electrode layer with the honeycomb structure 10 in contact. Thus, the metal electrode part 1 and the honeycomb structure 10 electrically connected. The contact of a part of each tongue piece 3 with the honeycomb structure 10 can for an electrical connection between the metal electrode part 1 and the honeycomb structure 10 and the contacting method is not limited. For example, the contact with the honeycomb structure 10 by elastic deformation of the tongue piece 3 can be maintained or the tongue piece 3 to the outer peripheral wall of the honeycomb structure 10 (or the electrode layer attached to the outer peripheral wall), or may be a fixing layer by thermal spraying a conductive metal material (for example, a NiCr-based material or a CoNiCr-based material) from an upper side of the tongue piece 3 be formed ago and can the tongue piece 3 to the outer peripheral wall of the honeycomb structure 10 (or the attached on the outer peripheral wall electrode layer) to be welded. In addition, when attaching each tongue piece needs 3 by forming the attachment layer, the "contact" between the part of the tongue piece 3 and the honeycomb structure 10 not necessarily being a physical contact, and even if between the tongue piece 3 and the honeycomb structure 10 there is a gap, are the metal electrode part 1 and the honeycomb structure 10 electrically connected via the conductive attachment layer so that the part of the tongue 3 and the honeycomb structure 10 in contact with each other. That is, as used herein, "contact" means not only physical but also electrical contact.

Thus, the metal electrode portion includes the plate-shaped main portion and the plurality of tongue pieces projecting from the main portion, and a portion of the tongue pieces contact the honeycomb structure, whereby the plurality of tongue pieces projecting from the main portion can be independently deformed along the outer peripheral wall of the honeycomb structure, so that even with poor dimensional accuracy of the honeycomb structure, a good electrical connection can be maintained. Further, the respective tongue pieces are individually deformed, whereby each tongue piece absorbs stress due to a difference in thermal expansion or the like. Therefore, it is possible to prevent excessive stress from being applied to the contact points and the honeycomb structure.

Further, each of the plurality of tongue pieces preferably satisfies the relationship 1 ≤ A / B ≤ 10. " A "Is a shortest length A from the main body 2 every tongue piece 3 projecting point to a furthest projected point of the tongue piece 3 , and " B "Is a minimum value B a width in one to the direction of protrusion from the main body 2 orthogonal direction on a surface of the tongue piece 3 ( 11 ).

As used herein, the "projecting position of the tongue piece" means a part where a vertical distance L to the main part 2 is the longest (see 11 (a) , (b)). In addition, the "shortest length A to a most protruding point of the tongue piece "is a straight line distance to a point at which a distance from the starting point of projecting each tongue piece 3 from the main body 2 of the tongue piece 3 shortest of points, at which a vertical distance to the main part 2 is the longest (see 11 (a) and 11 (b) ). 11 (a) shows A in the case of a flat plate shape in which a tip of each tongue piece 3 parallel to the main part 2 is, in the cross section of the main part 2 in the thickness direction, and 11 (b) shows A in the case where the tip of each tongue piece 3 has a curved surface shape, in the cross section of the main part 2 in the thickness direction.

The "direction of protrusion of each tongue piece 3 from the main part 2 "denotes one to the flow path direction of the cell 12 the honeycomb structure orthogonal direction X from the main body 2 of the tongue piece 3 projecting starting point along the surface of the tongue piece 3 (please refer 11 (c) and 11 (d) ). The "minimum value B a width in one to the direction of protrusion from the main body 2 orthogonal direction "denotes a width at a position where a width of a tongue piece 3 in one to the direction X vertical direction on the surface of the tongue piece 3 is the smallest (see 11 (c) and (d)).

11 (c) is a plan view of the metal electrode part 1 in the 11 (a) and 11 (b) . 11 (d) is a plan view of the tongue laid out in a plane 3 in 11 (c) , In the illustrated embodiment, the tongue contains 3 a neck; and a head with a wider width than that of the neck. The neck has a constant width so that the width of the neck is B.

With a ratio A / B of greater than or equal to 1, a plurality of tongue pieces projecting from the main portion can be easily deformed along the outer peripheral wall of the honeycomb structure, thereby making it possible to relieve a torsional stress applied to the tongue piece. Further, with a ratio A / B less than or equal to 10, the strength of the tongue piece can be maintained to some extent and prevent fatigue breakage of the tongue piece, as well as ensuring a width required for guiding a large current.

Furthermore, should be a length L1 the neck of each tongue piece 3 and a length L2 of the head preferably satisfy the relationship 1 ≦ L1 / L2 ≦ 10 (see 11 (d) ). At a ratio L1 / L2 greater than or equal to 1, a plurality of tongue pieces projecting from the main portion can be easily deformed along the outer peripheral wall of the honeycomb structure and degrade a torsional stress applied to the tongue piece. It can also be at a ratio L1 / L2 less than or equal to 10 maintains the strength of the tongue piece to some extent and prevents fatigue breakage of the tongue piece, as well as ensuring a width required to carry a high current.

It should be noted that neither the shape of the neck nor the shape of the head is limited, and if their appearances can be distinguished as a part having a relatively narrow width and a part having a relatively wide width, they can be considered as a neck Head are called.

Furthermore, each tongue piece contains 3 preferably two or more bent parts (see 12 ). The tongue piece containing two or more bent parts 3 can by taking advantage of the elastic deformation of the tongue piece 3 allow an improvement of a contact property with the honeycomb structure and a compensation of a stress exerted on the honeycomb structure mechanical stress.

Examples of one of the metal electrode parts 1 metals are, without limitation, representative of silver, copper, nickel, gold, palladium, silicon, and the like for ease of availability. The metal electrode part is preferred 1 an iron alloy, a nickel alloy or a cobalt alloy. It is also possible to use carbon or ceramic instead of the metal electrode part. Non-limiting examples of ceramics include at least one ceramic containing Si, Cr, B, Fe, Co, Ni, Ti, and Ta, and exemplified by silicon carbide, chromium silicide, boron carbide, chromium boride, and tantalum silicide. Composites can be formed by combining the metals with the ceramic.

Further, each metal electrode part 1 preferably a plurality of holes (see 11 (c) ). Thus, when the honeycomb structure generates heat, a heat-insulating effect of a conductive connecting member itself can be prevented and are temperatures of a front side and a back side of the metal electrode part 1 constant, so that on the inside of the metal electrode part 1 practiced Mechanical stress is reduced, which allows a deformation of the main part 2 to prevent. The plurality of holes may consist of through holes formed respectively by cutting the tongue piece from a single metal sheet. For example, they may be holes created by using a permeable material such as a mesh material, a sheet material having vent holes, and an expanded metal as a main part.

The carrier for an electrically heated catalyst according to the present invention may be used in an exhaust gas purification device. Thus, another aspect of the present invention is an exhaust gas purification device comprising: the support for the electrically heated catalyst according to the present invention, wherein the support is disposed in an exhaust gas flow path for flowing an exhaust gas from a motor; and a cylindrical metal member for receiving the support for the electrically heated catalyst. As apparent from the above descriptions, the exhaust purification device can achieve a required power line performance, so that a more stable exhaust gas purification function can be realized.

EXAMPLES

In the following, examples are presented for a better understanding of the present invention and its advantages, but the present invention is not limited to these examples.

Examples

Silicon carbide (SiC) powder and metallic silicon (Si) powder were mixed in a mass ratio of 60:40 to prepare a ceramic raw material. To the ceramic raw material, hydroxypropylmethyl cellulose as a binder, a water-absorbent resin as a pore-forming agent and water were added to form a molding raw material. The molding raw material was then kneaded by means of a vacuum green body kneader to prepare a round columnar green body. The binder content was 7 mass parts when the total amount of the silicon carbide (SiC) powder and the metallic silicon (Si) powder 100 Mass parts amounted. The pore former content was 3 parts by mass when the total amount of the silicon carbide (SiC) powder and the metallic silicon (Si) powder 100 Mass parts amounted. The water content was 42 Parts by mass, when the total amount of the silicon carbide (SiC) powder and the metallic silicon (Si) powder 100 Mass parts amounted. The average particle diameter of the silicon carbide powder was 20 μm, and the average particle diameter of the metallic silicon powder was 6 μm. The average particle diameter of the pore-forming agent was 20 μm. The average particle diameter of both the silicon carbide powder and the metallic silicon powder as well as the pore-forming agent corresponds to a volume average arithmetic mean when measuring the frequency distribution of a particle size by the laser diffraction method.

The resulting columnar green body was formed by an extruder to obtain a columnar honeycomb shaped body in which each cell had a square cross-sectional shape. The resulting honeycomb formed body was subjected to high-frequency dielectric heating and drying, and then dried at 120 ° C for 2 hours by means of a hot-air dryer, and a predetermined amount of both end faces was cut to prepare a dried honeycomb body. The dried honeycomb body was degreased (calcined) and then fired.

Then, hydroxypropylmethyl cellulose as a binder, glycerin as a humectant, a wetting agent as a dispersant and water were added to metallic silicon (Si) powder, and the whole was mixed together. The mixture was kneaded to prepare an electrode layer-forming raw material. The electrode layer-forming raw material was then applied in a strip form on the side surface of the fired honeycomb body so as to extend between the two end faces of the fired honeycomb body so that a thickness was 1.5 mm. The electrode layer-forming material was applied at two positions on the side surface of the fired honeycomb body. Then, in the cross section orthogonal to the extension direction of the cell, one of the two parts covered with the electrode layer forming material was placed on an opposite side to the other over the center of the fired honeycomb body.

The electrode layer-forming raw material applied to the fired honeycomb was then dried to obtain a fired honeycomb body with unfired electrodes. The drying temperature was 70 ° C.

Subsequently, the fired honeycomb body was degreased (calcined) with unfired electrodes, fired, and further oxidized to obtain a honeycomb structure. The degreasing was carried out at 550 ° C for 3 hours. Firing took place at 1450 ° C for 2 hours in an Ar atmosphere. The oxidation was carried out at 1300 ° C for 1 hour. Each of the end faces of the resulting honeycomb structure had a round shape with a diameter of 80 mm, and the length of the honeycomb structure in the extending direction of the cell was 75 mm.

Then, metal electrode portions each having a matching to the outer peripheral wall of the honeycomb structure, curved plate-shaped main part (stainless steel material); and one in each 11 Shaped tongue pieces (stainless steel material) were respectively disposed on outer peripheral surfaces of electrode layers of the honeycomb structure so as to face each other across a center of the honeycomb structure, and a tip of each tongue piece was fixed to an electrode layer from a top of the tongue piece by a welding method. Specific indices of the tongue pieces of each of the examples and the comparative example are shown in Table 1.

Comparative example

The preparation was carried out under the same conditions as those of the examples, except that the metal electrode member was replaced with a comb-shaped electrode having no tongue pieces.

Honeycomb break check

Each honeycomb structure in which tongue pieces (or comb-shaped electrodes) were fixed by welding was subjected to a vibration test in which the honeycomb structure was wrapped with a ceramic mat and then housed in a metal container, and oscillated at a frequency of 100 Hz and an acceleration of 30 g applied for 24 hours. Broken states of welded parts / honeycomb structure were visually confirmed. The number of visually confirmed broken specimens is shown in Table 1.
Table 1 Tongue Shape (mm) Number of fractions A (L1) B L2 Comparative example - 13/20 example 1 2 2 2 2/20 Example 2 10 2 10 1.20 Example 3 20 2 10 0/20 Example 4 20 2 2 0/20

discussion

From the results shown in Table 1, it can be seen that the examples, as compared with the comparative example, effectively suppress breakage of the welded parts / honeycomb structure. On the other hand, the comparative example using the metal electrode parts having no tongue pieces resulted in insufficient stress relaxation and a larger number of breaks of the welded parts / honeycomb structure.

LIST OF REFERENCE NUMBERS

10

honeycomb structure

11

partition wall

12

cell

1, 1A, 1B, 1C

Metal electrode part

7A, 7B, 7C, 7D, 7E, 7F, 7G

tongue piece

101a, 101b

electrode layer

2

Bulk

3, 13, 23, 33

tongue piece

3a, 13a, 23a, 33a

increasing part

3b, 13b, 23f, 33c

shallow part

20

one piece

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• JP 5761161 B [0006]

Claims (8)

Support for an electrically heated catalyst, comprising: a honeycomb structure; and a pair of metal electrode parts, wherein a metal electrode part of the pair of metal electrode parts is disposed on a side opposite to the other metal electrode part across a center of the honeycomb structure; wherein a part or both of the pair of metal electrode parts contains or contains: a plate-shaped body; and a plurality of tongue pieces respectively protruding from the main body, and wherein a part of each tongue piece is in contact with the honeycomb structure. Support for the electrically heated catalyst after Claim 1 wherein each of the plurality of tongue pieces satisfies 1 ≦ A / B ≦ 10, where A is a shortest length A from a starting point protruding from the main part of each tongue piece to a most protruding position of the tongue piece, and B is a minimum value B a width in a direction orthogonal to a direction of protrusion from the main part on a surface of each tongue piece. Support for the electrically heated catalyst after Claim 1 or 2 wherein each of the tongue pieces includes: a neck; and a head having a width wider than a width of the neck, and wherein a length L1 of the neck and a length L2 of the head satisfy the relationship 1 ≦ L1 / L2 ≦ 10. Support for the electrically heated catalyst according to one of Claims 1 to 3 wherein each of the tongue pieces includes two or more bent parts. Support for the electrically heated catalyst according to one of Claims 1 to 4 wherein the honeycomb structure includes a pair of electrode layers on a side surface of the honeycomb structure, and wherein an electrode layer of the pair of electrode layers is disposed on an opposite side of the other electrode layer over the center of the honeycomb structure. Support for the electrically heated catalyst according to one of Claims 1 to 5 wherein each of the metal electrode parts includes an iron alloy, a nickel alloy or a cobalt alloy. Support for the electrically heated catalyst according to one of Claims 1 to 6 The main part has a plurality of holes. An exhaust gas purification device, comprising: the support for the electrically heated catalyst according to any one of Claims 1 to 7 wherein the carrier is disposed in an exhaust gas flow path for flowing an exhaust gas from a motor; and a cylindrical metal member for receiving the support for the electrically heated catalyst.

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